In recent years, with a decrease in the size and the weight of electronic instruments, small-sized and large-capacity capacitors for high frequencies have been desired. As such capacitors, developments have been advanced about electrolytic capacitors small in equivalent series resistance (ESR) and excellent in frequency properties. Electrolytic capacitors each include an anode body including a valve action metal such as tantalum, niobium, titanium or aluminum, a dielectric layer formed on the anode body, and a cathode body. Out of these electrolytic capacitors, the following are also called solid electrolytic capacitors: electrolytic capacitors in each of which a conductive polymeric layer containing a conductive polymeric layer (solid electrolytic layer) is formed as a cathode member on a dielectric layer.
In order to heighten the conductive polymeric layer in strength, investigations have been made about the use of a crosslinking agent when the conductive polymeric layer is formed. For example, according to Patent Literature 1, a conductive polymeric layer (polymeric outer layer) is formed by: forming a solid electrolytic layer containing a conductive polymer; immersing this layer into a solution containing a crosslinking agent and then drying the layer; and immersing the layer into a liquid dispersion containing a conductive polymer and then drying the layer. According to Patent Literature 1, in order to restrain the conductive polymeric layer of a capacitor element from being peeled off and make the conductive polymeric layer high in performance of covering terminal portions of the capacitor element, the crosslinking agent is used before the formation of the polymeric outer layer, as described above.